A plurality of modules may be coupled to a bus. In order to individually access each of the plurality of modules, each module should have a unique identifier, i.e., address. In some cases, the modules may be initially manufactured identically with added process step(s) to set an individual address for each module. For example, an array of switches may be used to set an address for a module. In another example, each resistor in an array of resistors may be coupled to VCC (e.g., a positive voltage supply) or VSS (e.g., ground or a negative voltage supply) to provide an address for a module. In another example, the address of the module may be stored in memory prior to coupling the module to the bus.
In all of the these examples, the addresses are set at manufacturing or, at least, individually, prior to coupling the modules to a bus. Manufacturing costs may be increased because of the additional step(s). Further, modules with individual addresses set must be individually identified so two modules with the same address are not connected to the same bus. This may add to the cost of inventory as well as including a risk of two modules with the same address being connected to the bus. In these examples, changing a module's address typically requires direct access to the module, making maintenance and system expansion difficult.
It is desirable for each module to be manufactured identically to each other module, providing savings in both manufacturing cost and time. In operation, however, it is desirable to individually access each module using, e.g., a unique address for each module.